Buxus balearica

Key to letters a. Buxus balearica WiWd. b. Buxusmalayana RidX. c. Buxus microphylla Sieb. etZucc. vox. sujfruticosa Makino d. Buxus rolfei Vidal e. Buxus sempervirens L. 

Acetylation and reduction with sodium borohydride of (106a) led to (109) dehydrated to (110). Lithium aluminium hydride reduction of the oxiran ring of (110) afforded the tertiary alcohol (111) identical to N-isobutyrylbuxaline F, isolated from Buxus balearica whereby structure and stereochemistry were established. 

On treatment with iV-bromoacetamide followed by alkali the olefin (46), a pyrolysis product of yV-isobutyrylcyclobuxidine F, afforded the corresponding 1/3,10/3-epoxide.The latter was readily transformed into (47) which was found to be identical with A -isobutyrylbuxaline F, an alkaloid from Buxus balearica. p-Nitroperbenzoic acid converted (48) into the la,10a-epoxide (49). Successive treatment of (49) with triphenylphosphine and sodium methoxide afforded the novel cyclopropane derivative (50). 

Cycloxobuxines 149). JV-Isobutyroylcycloxobuxine-F(R = Me2CHCO-), isolated from Buxus balearica, has been described as baleabuxine. Recently, it has been isolated by Russian workers from the same Buxus species. 

The structures of previously isolated alkaloids A, D, and G from Buxus balearica have been elucidated.25 Alkaloid D has been identified as JV-isobuty-roylcycloxobuxidine F,26 alkaloid G as cycloxobuxidine F, and, although alkaloid A has an n.m.r. spectrum similar to N-isobutyroylcycloxobuxine F (baleabuxine),27 the mixed melting point of these two alkaloids suggested that they were dissimilar. Alkaloid A is thought to be epimeric with baleabuxine and has been named pseudobaleabuxine. 

N-3-Isobutyrylbuxidienine-F and N-Benzoylbuxidienine-F. N-3-Isobutyrylbuxidienine-F (226) and iV-benzoylbuxidienine-F (227) were isolated from Buxus balearica Willd. (10), the former also from B. balearica Lam. (99) and the latter from B. sempervirens (S8a). Their structures were elucidated independently by two research groups both results were based on physical data. 

Pseudobaleabuxine-F (C3oHgoN202 mp 236-240° [aj + 120.7°)was isolated from the leaves of Buxus balearica 98, 99, 104). According to the spectroscopic data this seemed to be iV-3-isobutyrylcycloxobux-ine-F (baleabuxine-F) (222). Direct comparison of pseudobaleabuxine-F with an authentic sample of 222 showed a depression in the mixed melting point, and therefore it was concluded that the alkaloid under study is an epimer of 222. The structural difference, however, has not been ascertained. 

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